Preparation of single atom catalysts for high sensitive gas sensing

Single atom catalysts(SACs)have garnered significant attention in the field of catalysis over the past decade due to their exceptional atom utilization efficiency and distinct physical and chemical properties.For the semiconductor-based electrical gas sensor,the core is the catalysis process of target gas molecules on the sensitive materials.In this context,the SACs offer great potential for highly sensitive and selective gas sensing,however,only some of the bubbles come to the surface.To facilitate practical applications,we present a comprehensive review of the preparation strategies for SACs,with a focus on overcoming the challenges of aggregation and low loading.Extensive research efforts have been devoted to investigating the gas sensing mechanism,exploring sensitive materials,optimizing device structures,and refining signal post-processing techniques.Finally,the challenges and future perspectives on the SACs based gas sensing are presented.

Electrically-pumped compact topological bulk lasers driven by band-inverted bound states in the continuum

One of the most exciting breakthroughs in physics is the concept of topology that was recently introduced to photonics,achieving robust functionalities,as manifested in the recently demonstrated topological lasers.However,so far almost all attention was focused on lasing from topological edge states.Bulk bands that reflect the topological bulk-edge correspondence have been largely missed.Here,we demonstrate an electrically pumped topological bulk quantum cascade laser(QCL)operating in the terahertz(THz)frequency range.In addition to the band-inversion induced in-plane reflection due to topological nontrivial cavity surrounded by a trivial domain,we further illustrate the band edges of such topological bulk lasers are recognized as the bound states in the continuum(BiCs)due to their nonradiative characteristics and robust topological polarization charges in the momentum space.Therefore,the lasing modes show both in-plane and out-of-plane tight confinements in a compact laser cavity(lateral size~3λ_(laser)).Experimentally,we realize a miniaturized THz QCL that shows single-mode lasing with a side-mode suppression ratio(SMSR)around 20 dB.We also observe a cylindrical vector beam for the far-field emission,which is evidence for topological bulk BIC lasers.Our demonstration on miniaturization of single-mode beam-engineered THz lasers is promising for many applications including imaging,sensing,and communications.

Recent advances in preparation,properties and device applications of twodimensional h-BN and its vertical heterostructures

Two-dimensional（2D） layered materials,such as graphene,hexagonal boron nitride（h-BN）,molybdenum disulfide（Mo S_2/,have attracted tremendous interest due to their atom-thickness structures and excellent physical properties.h-BN has predominant advantages as the dielectric substrate in FET devices due to its outstanding properties such as chemically inert surface,being free of dangling bonds and surface charge traps,especially the large-band-gap insulativity.h-BN involved vertical heterostructures have been widely exploited during the past few years.Such heterostructures adopting h-BN as dielectric layers exhibit enhanced electronic performance,and provide further possibilities for device engineering.Besides,a series of intriguing physical phenomena are observed in certain vertical heterostructures,such as superlattice potential induced replication of Dirac points,band gap tuning,Hofstadter butterfly states,gate-dependent pseudospin mixing.Herein we focus on the rapid developments of h-BN synthesis and fabrication of vertical heterostructures devices based on h-BN,and review the novel properties as well as the potential applications of the heterostructures composed of h-BN.